Firstly you never actually own the car. While some are OK with that I am very fond of being able to say "something's mine".
As Rich said after 2 years you have NOTHING. You're basically renting a car.
10k a year is simply not enough for the average person who does 200 miles a week that is already 10,400 miles .
The reason they're doing it is simple, it's happening to loads of cars, 135m, BMW M5 F60 or whatever it is (the new stupid one) , Merc AMGs, it's so that in 2 years the market is flooded with fully dealer serviced models with 20k or less on the clock that can easily be flogged on in car dealerships.
If you had NO car now and wanted a new car it would be worth considering but if you have a car already you're basically paying for a really expensive taxi service .